Basal Nuclei

Basal Nuclei

\- give fibers/pathway for neurotransmitters which are essential in regulating the function of the brain

\- applied to a collection of masses of gray matter situated within each cerebral hemisphere

\- they are the corpus striatum, amygdaloid nucleus, and claustrum

Lentiform Nucleus

composed of the globus pallidum and putamen.

Corpus Striatum

\- composed of the caudate nucleus and the lentiform nucleus

Neostriatum

\- composed of the caudate nucleus and putamen

\- important since it has a direct connection with the cortex of the brain

\- it is the first to receive neurotransmitters

Amygdaloid Body

\- found at the tail of the caudate nucleus

\- anatomically not a part of the basal ganglia but instead, it is a part of the limbic system

* Caudate Nucleus
* Globus Pallidus
* Putamen

most important basic structures of the basal ganglia.

Caudate Nucleus

\- composed of the head, body, and tail

\- c-shaped

\- it is closed to the lateral ventricle; cross section: close to the lateral portion of the thalamus

\- receives many information (glutamate) including info from the cortex, striatum, and thalamus

Caudate Nucleus

\- implicated for:

* voluntary movement because of the cortex
* learning and memory because of its direct link with hypothalamus
* memory and sleep because of its direct connection with the brain stem (reticular formation)
* addiction to drug abuse

* Nucleus Accumbens
* Caudate Nucleus

two nucleus concerned for addiction to drug abuse.

Nucleus Accumbens

\- plays a major role in addiction behavior

\- area of the brain where the feeling of pleasure or satisfaction goes

\- has a connection with the caudate nucleus which is why it is also implicated for social behavior

Lentiform Nucleus

\- is related laterally to a thing sheet of white matter (external capsule)

\- gives signal to the thalamus

\- is made up of the putamen and globus pallidus and is separated by a thin sheet of gray matter which is the claustrum

\- “lente” or telescope; wedge shaped

Putamen

means shell-shaped.

Globus Pallidus

has a pallid/pale appearance.

Amygdaloid Nucleus

\- situated in the temporal lobe close to the uncus

\- part of the limbic system; can influence the body’s response to environmental changes

\- has a direct connection with the tail of the caudate nucleus

Claustrum

\- thin sheet of gray matter that is separated from the lateral surface of the lentiform nucleus by the external capsule

\- function is still unknown

Corticostriate Fibers

\- from the cerebral cortex, it sends axon to putamen and caudate nucleus

\- *neurotransmitter:* ***glutamate***

\- excitatory in function

Thalamostriate Fibers

\- intralaminar nuclei of the thalamus send large numbers of axons to the caudate nucleus and the putamen

\- excitatory in function

Nigrostriate Fibers

\- neurons in the substantia nigra send axons to the caudate nucleus and the putamen and liberate ***dopamine*** at their terminals as the neurotransmitter

\- both inhibitory and excitatory in function

Brainstem Striatal Fibers

\- ascending fibers from the brainstem end in the caudate nucleus and putamen and liberate ***serotonin*** at their terminals as the neurotransmitter

\- inhibitory in function

Striatopallidal Fibers

\- pass from the caudate nucleus and putamen to the globus pallidus

\- neurotransmitter: ***GABA***

\- inhibitory in function

Striatonigral Fibers

\- pass from the caudate nucleus and putamen to the substantia nigra

\- neurotransmitter: ***GABA***

\- some of the fibers use GABA or acetylcholine as the neurotransmitter, while others use substance P

Striatopallidal Fibers

\- pass from the caudate nucleus and putamen to the globus pallidus

\- neurotransmitter: ***GABA***

Pallidofugal Fibers

\- can be divided into 4 groups:

* Ansa Lenticularis
* Fasiculus Lenticularis
* Pallidotegmental Fibers
* Pallidosubthalamic Fibers

Ansa Lenticularis

pass to the thalamic nuclei.

Fasciculus Lenticularis

pass to the subthalamus.

Pallidotegmental Fibers

terminate in the caudal tegmentum of the midbrain.

Pallidosubthalamic Fibers

pass to the subthalamic nuclei.

Chorea

\- patients exhibit involuntary, quick, jerky, irregular movement that are non repetitive (e.g. swift grimaces and sudden movement of the head or limb)

\- usually an affectation of the distal extremities and head

\- movements are not as big as hemiballismus

\- general term

Hemiballismus

\- form of involuntary movement confined to one side of the body

\- usually involves the proximal extremity musculature, and the limb suddenly flies about out of control (flailing) in all directions

\- lesion occurs in the opposite subthalamic nucleus or its connections

Subthalamic Nucleus

where the smooth movements of different parts of the body are integrated.

Parkinson’s Disease

\- progressive disease of unknown cause that commences between the ages of 45 and 55 years

\- associated with neuronal degeneration in the substantia nigra and, to a lesser extent, in the globus pallidus, putamen, and caudate nucleus

\- degeneration of the neurons of the substantia nigra that send their axons to the corpus striatum results in a reduction in the release of dopamine within the corpus striatum - leads to hypersensitiviy og the dopamine receptors in the postsynaptic neurons in the striatum

Direct Pathway

pathway that facilitates movement.

Indirect Pathway

pathway that inhibit movement.

Athetosis

\- consists of slow, sinuous, writhing movement that most commonly involve the distal segments of the limbs

\- degeneration of the globus pallidus occurs with a breakdown of the circuitry involving the basal nuclei and the cerebral cortex

Athetoid Cerebral Palsy

characterized by twisting of limbs, head, or tongue.

Hyperbilirubinemia

common cause of cerebral palsy.

Cerebal Palsy

injury to the developing brain.

Traumatic Brain Injury

injury to the developed brain.